JPS6345537A - Chemiluminescence type ammonia analyzing instrument - Google Patents

Abstract

PURPOSE:To permit measurement of ammonia of low concn. in a measurement range of a small full scale by supplying gaseous O3 of the concn. lower than the concn. of gaseous NO to a system up to a detector and oxidizing the gaseous NO in the gas by as much as the amt. of the gaseous O3 to convert said gas to gaseous NO2. CONSTITUTION:A converter 3 provided to permit reduction contact catalysis is disposed to the system 1 and the top ends of the probe part 4 of the respective systems 1, 2 are disposed to face a flue 5. A scrubber part 6, a pretreatment part 7, a flow rate control part 8 and chemiluminescence chambers 9 which are the detecting part are connected to the inflow line for the gas to be measured of the respective systems. Ozone supply lines 11 for supplying the gaseous O3 from ozone generating parts 10 are piped to the respective chambers 9. The measurement of the concn. of the gaseous NO is executed by chemiluminescence analysis and the concn. is calculated by an arithmetic part 12 and is displayed on a display part 13. The respective ozone generating parts 10 of the respective systems and the inflow line for the gas to be measured are connected by ozone introducing paths 14 so that the gaseous O3 of the concn. lower than the concn. of the gaseous NO in the gas to be measured is supplied.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a chemiluminescent ammonia analyzer that is attached to pollution prevention equipment such as flue gas denitrification equipment and measures the concentration of ammonia gas contained in gas. Regarding.

[Conventional technology]

It is generally called the Chemilumi method, in which NO (-nitrogen oxide) gas is used at 0. This is a chemiluminescent ammonia analyzer that uses a photomultiplier tube to detect the intensity of light emitted when it reacts with (ozone).

NH, gas and NO introduced from the gas introduction part to be measured
The first series passes the measured gas coexisting with a gas through a converter equipped with a reduction catalyst or oxidation catalyst, and the detector detects the NO gas concentration in the gas after passing through the converter. and a second system that detects the NO gas concentration in the gas that does not pass through the converter with a detector different from the above, and compares and calculates the output of each detector in these two systems. The structure is such that the NH3 gas concentration in the gas to be measured is measured.

The measurement principle of a reduced ammonia analyzer is to provide two sampling lines, one of which
, a converter equipped with a reduction catalyst is interposed in the series, and the gas to be measured is passed through the converter to produce NO+NH,+1/40. =N, +3/2H,0 reaction is carried out. This reaction is an equimolar reaction between NO gas and NH gas in the coexistence of 02, so on the metal plate,
Considering the case where 5 ppm of NH gas and 150 ppm of NO gas coexist in the gas to be measured, the NO gas concentration in the gas after one reaction is 1l50-5=145 pp.

On the other hand, since the other NOx series is not equipped with a converter, the NO gas concentration in the measured gas is 150 pp.
m is directly detected by the analyzer. The difference between these two series,
That is, (NO) - [NONH3) = 150 14
5 = 5 p p m = [NH3] is obtained as the final output amount, and the NH3 gas concentration is measured.

The measurement principle of an oxidized ammonia analyzer is
Similarly, two sampling lines are provided, and one of the lines is equipped with a converter equipped with an oxidation catalyst.
By passing the gas to be measured through the converter, NH, +5/40. =N O+3/2H20 reaction is carried out. Due to this reaction, NH3 gas is oxidized and turns into NO gas with an equimolar amount, so in the same way as above, 5ppm of NH3 gas and 150ppm of NH3 gas in the gas to be measured.
Considering the case where m NO gas coexists, the NO gas concentration in the gas after reaction is 150 + 5 = 155 p
p m. On the other hand, since the other series is not provided with a converter, the NO gas concentration of 150 ppm in the gas to be measured is directly detected by the analyzer. The difference between these two series, ie.

(NO+N)(3)-(NO)=155-150=
5 pp m=(NH3) is obtained as the final output signal, and the NH3 gas concentration is measured.

[Problem that the invention seeks to solve]

The conventional chemiluminescent ammonia analyzer described above exhibits excellent characteristics such as low interference effects and excellent sensitivity and stability, but when determining the NH and gas concentrations, the NO gas concentration of each series is measured, and the The NH gas concentration is calculated from the gas concentration.On the other hand, since the NO gas concentration in the measured gas is considerably higher than the NH gas concentration, the NH gas concentration is calculated from the NH gas concentration.
, Even though the gas concentration is extremely low, measurements must be performed using a large full-scale concentration measurement range.As a result, the ratio of the NH and gas concentration to the full-scale concentration is small, resulting in poor analysis accuracy. For example, since the concentration of NO gas in the gas to be measured is usually between 100 and 200 ppm, the measurement range of the analyzer must be selected to have a full-scale concentration of approximately 250 ppm. . On the other hand, since the NH gas concentration is usually about O to 110PP, 250pp
The value is only about 0 to 4% with respect to the m full-scale concentration. For this reason, in conventional devices, the output value is electrically expanded to obtain an apparently small full-scale concentration measurement range, but simply expanding the output value in this way does not improve the apparent reading accuracy. However, no essential improvement in accuracy has been achieved.

This invention focuses on the fact that an ammonia analyzer using the Chemilumi method is a two-system differential calculation system, and makes it possible to measure NO by setting the measurement range to a small full-scale concentration, which essentially improves the accuracy of the ammonia analyzer. The challenge is to increase the

[Means for solving problems]

In order to achieve the above object, the present invention provides an ammonia analyzer with the following configuration. In other words, the gas to be measured, in which NH, gas, and NO gas coexist, is introduced from the gas inlet to be measured and passed through a converter equipped with a reduction catalyst or an oxidation catalyst, and after passing through the converter, the NO gas in the gas is reduced. The first series detects the concentration with a detector, and also the N in the gas that does not pass the gas to be measured through the converter.

and a second series in which the gas concentration is detected by a detector different from the above, and the outputs of the respective detectors in both series are compared and calculated to determine the NH in the gas to be measured.

In a chemiluminescent ammonia analyzer for measuring gas concentration, ozone generated from an ozone generator is introduced into each gas flow path up to each of the detectors of the first series and the second series. The gist of this paper is a chemiluminescence type ammonia analyzer characterized by having an ozone introduction path in communication.

[For production]

In the ammonia gas analyzer according to the present invention having the above-mentioned configuration, the first line and the second line leading to the detector have a concentration of 0.000 ml of gas lower than the NO gas concentration. When gas is supplied, NO gas in each series of gas to be measured becomes ○
, it is oxidized by an amount corresponding to the gas concentration and turns into N○2 gas. Therefore, chemiluminescence is no longer produced in the detection section by the reaction amount, and only the remaining unreacted NO gas is detected in the detector. Then, as in the conventional case, the NH and gas concentrations are measured from the difference between the detected values of both series. Therefore, the measurement range of the detector is the remaining N
.

It becomes possible to select one with a small full-scale concentration corresponding to the gas.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 is a schematic diagram of a reduced type ammonia analyzer according to the present invention, and Fig. 2 is a diagram showing the ratio of NH3 gas 1 degree value to each full-scale concentration in the conventional device and the device of the present invention. It is.

This reduced type ammonia analyzer is equipped with two series of measurement gas inflow lines: a first series that is an NH3 series, and a second series 2 that is an NO series. The first series 1 is provided with a converter 3 provided with a reduction catalyst, and the tips of the probe sections 4 of each series 1.2 are made to face the flue 5. A scrubber section 6, a pretreatment section 7, a flow rate control section 8, and a chemirumi chamber 9 serving as a detection section are connected in sequence to the gas inflow line to be measured in each series following the probe section 4. And, in each Chemilumi chamber 9,
0 from the ozone generating section 10. An ozone supply line 11 for supplying gas is installed. Further, the NO gas concentration in each chemiluminescence chamber 9 is measured by chemiluminescence analysis, and the NO gas concentration is calculated by the calculation section 12 and displayed on the display section 13. The above configuration is the same as the conventional reduced ammonia analyzer described above.

In the analyzer having the above configuration, the present invention connects each of the ozone generators IO and the gas inflow line to be measured in each series via an ozone introduction path 14 between the pretreatment section 7 and the flow rate control section 8. The structure is characterized in that the 03 gas is supplied with a concentration lower than the NO gas concentration in the gas to be measured which has flowed from the flue 5 into each of the gas inflow lines to be measured.

In the ammonia analyzer configured as above, the flue 5
The gas to be measured that has flowed into the gas inflow line of each series flows through each part of each gas inflow line to reach the Chemiluminium chamber 9. For example, 10Pp
The gas to be measured, in which m NH, gas and 200 ppm NO gas coexist, undergoes the above-mentioned reaction when it comes into contact with the reduction catalyst of the converter 3 of the probe section 4, and a portion of the NO gas is mixed with NH, gas, etc. It undergoes a molar reaction and turns into N2 gas, and the NO gas concentration becomes 190PPm. On the other hand, since this series is not provided with a converter, the gas to be measured that has flowed into the gas to be measured inflow line of the second series 2 is N
The O gas concentration remains unchanged at 200 ppm. and,
When gas is supplied from the ozone generator 10 to each series up to the Chemilumi chamber 9 through the ozone introduction path 14 at a concentration lower than NO gas, for example 150 ppm, NO+O,=NO2+02'i') A reaction occurs in each series, and the NO2 is not detected in each Chemiluminium chamber 9, but the remaining N.

gas, i.e. 40 PPm NO in the first series
In the second series, 50 ppm of NO gas was detected by chemiluminescence due to reaction with the gas, and the NO gas concentration of 10 ppm was detected, which is the difference between the two series. Therefore, the NH3 gas concentration of 10 ppm was detected. It will be measured. Therefore, the measurement range in the detection section can be set to a full scale concentration of 50 PPm. In this regard, to measure NO gas at a concentration of 200 ppm, a full scale concentration of 250 p
Compared to the conventional case where the measurement range is pm,
It will look like Figure 2. That is, a concentration of 10 ppm of N
When H, gas is measured in a 250 ppm full scale range, it is only 4% of the full scale, but in a 50 ppm full scale range, it is 20% of the full scale. By setting the concentration of NO gas to 50 ppm or less in this way, it is possible to set the full scale concentration to a small measurement range of 50 ppm, and there is no need to expand the gain of the calculation section. Rather than an apparent improvement in reading accuracy by expanding the gain as in the prior art, an essential improvement in accuracy is achieved.

In the above embodiments, a reduction type ammonia analyzer was described in which the gas to be measured is brought into contact with a reduction catalyst, but the gas to be measured is brought into contact with an oxidation catalyst to oxidize NH, converting it to NO, and then making the measurement. It goes without saying that this invention can also be applied to an oxidized ammonia analyzer. Also.

Although we have described a system in which a fixed amount of O and gas are supplied between the flow rate control section and the pretreatment section of each series, the present invention is not limited to this. 03 gas may be introduced.

〔effect〕

As explained above, according to the present invention, there is a first series for measuring the NO gas concentration after passing the gas to be measured through the converter, and a first series for measuring the NO gas concentration after passing the gas to be measured through the converter; Since an ozone introduction path that can supply 0° lower than the NO concentration is provided in the gas inflow line to be measured up to each detection part of the second series that measures the NO gas concentration in the case of a low concentration. Since ammonia can be measured in a small full-scale concentration measurement range without expanding the gain of the detection section, the analysis accuracy in the ammonia analyzer can be improved. Furthermore, since there is no need to expand the gain of the detection section, there is no need to worry about the increase in instrumental error that would otherwise occur due to range expansion in the arithmetic section.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of the ammonia analyzer according to the present invention, and FIG. 2 shows the ratio of NH and gas concentration values to each full-scale concentration in the device of the present invention and the conventional device. It is a diagram. 1...First series, 2...Second series, 3...
...Converter, 4...Probe part, 6...
- Part of the scrubber, 7... Pretreatment section, 8... Flow rate control section, 9... Chemiluminium chamber. 10... Ozone generation section, 11... Ozone supply line. 12... Arithmetic unit, 13... Instruction unit, 14
...Ozone introduction path.

Claims (1)

[Claims] NH_3 gas and N introduced from the gas introduction part to be measured
A first step in which the gas to be measured in which O gas coexists is passed through a converter equipped with a reduction catalyst or an oxidation catalyst, and the NO gas concentration in the gas after passing through the converter is detected by a detector.
series, and similarly the gas to be measured does not pass through the converter,
A second system detects the NO gas concentration in the gas that does not pass through the converter with a detector different from the above, and the output of each detector in both systems is compared and calculated to detect the NH_3 concentration in the gas to be measured. In a chemiluminescent ammonia analyzer for measuring gas concentration, ozone generated from an ozone generator is introduced into each gas flow path up to each of the detectors of the first series and the second series. A chemiluminescence type ammonia analyzer characterized in that an ozone introduction path is connected.